<div class="login">
    <div class="row">
        <div class="col-sm-12">
            <div class="form">
                <div class="form-group">
                    <label for="username">用户名</label>
                    <input type="text" id="username" class="form-control">
                </div>
                <div class="form-group">
                    <label for="password">密码</label>
                    <input type="password" id="password" class="form-control">
                </div>
                <div class="form-group">
                    <button class="btn btn-primary">登录</button>
                </div>
            </div>
        </div>
    </div>
</div>